A mass-produced car frame is normally made of metal (steel or aluminum). To improve the mechanical characteristics and reduce the weight of racing cars, frames made of composite material (typically carbon or Keviar® which is a registered trademark of DuPont for a para-aramid synthetic) fibre having been introduced, the commonest of which substantially comprises a single monolithic body made of hand-laminated carbon and/or Kevlar fibre.
A mass-produced car frame of composite material normally comprises a central body defining the passenger compartment, made of hand-laminated carbon and/or Keylar®. fibre, and to which are bolted a front and rear body also made of hand-laminated carbon and/or Kevlar® fibre. This solution is selected to simplify and reduce the cost of repairing the ear in the event of an accident. Composite materials, in fact, are difficult to repair, especially in other than specialized workshops, and, when damaged, are preferably replaced. An example of a car frame made entirely of composite material is described in Patent Application GB-2317858-A.
Frames made of composite material fibre have better mechanical characteristics and are lighter than metal frames, but are much more expensive and take much longer to produce. This is the reason in the case of road vehicles, that composite material fibre frames are currently limited to high-performance cars produced in very small numbers (at most one or two cars a day).
In the case of mass-produced vehicles, only single parts made of composite material fibre have so far been proposed, as described for example in Patent Application EP-1316409-A1, which relates to a truncated-cone-shaped insert for gradually absorbing the energy of a head-on collision. Another example of a car featuring a front insert of composite material for gradually absorbing the energy of a head-on collision is described in U.S. Pat. No. 6,698,822-B1.
EP-0291385-A1 discloses a modular structure for a vehicle comprising a front module which is simultaneously load-bearing in order to receive stresses and loads, and supporting in order to receive sub-assemblies and their accessories, a central module for absorbing substantial shocks, and a rear module formed from two side rails with a J-shaped horizontal profile.